Finger-operated pumps are conventionally employed with a suitable nozzle structure as part of a closure at the top of a liquid product container, such as a metal can, glass bottle, or plastic bottle. Depending upon the nozzle structure, the liquid may be discharged as a jet stream, a spray, an atomized fine spray, a foam, or other suitable form. Such pumps may be used to dispense a wide variety of liquid products such as cleaners, hair styling preparations, perfumes, deodorants, throat sprays, air fresheners, lotions, and the like.
U.S. Pat. No. 4,025,046 issued to Michel Boris discloses a number of prior art designs for finger-operated dispensing pumps. One design includes a pump chamber with an internally disposed, upwardly projecting, supply conduit having an open upper end and having a lower end connected at the bottom of the chamber to a suction tube extending down into the container of liquid.
A piston is slidably disposed in the pump chamber and includes a piston rod extending upwardly out of the top of the pump chamber to the nozzle. A discharge passageway is defined in the piston and rod to provide communication between the pump chamber and the nozzle.
A poppet is provided with a valve member to seal against a valve seat on the piston, and the poppet is normally biased against the piston by a spring so as to occlude flow through the discharge passage to the nozzle. The poppet also has an outer pressure-bearing surface exposed in the pump chamber at all times. A generally cylindrical sleeve extends downwardly from the poppet and is spaced above the supply conduit when the pump is in the inactive position.
When the piston is displaced downwardly in the pump chamber, as by pushing down on the top of the nozzle, the poppet is pushed against the spring and the poppet sleeve telescopically slides down over the suction conduit open upper end to seal around the suction conduit. The pressure of the liquid and residual gas within the pump chamber then increases as the piston is pushed down further. The increasing pressure acting upwardly on the piston is opposed by the finger force exerted downwardly on the piston, and the increasing pressure acting downwardly on the poppet pressure-bearing surface produces a force acting through the poppet against the spring. When this pressure increases sufficiently to overcome the spring force, the poppet moves further downwardly in the pump chamber, still sealing against the supply conduit, so that the poppet valve member moves away from the piston thereby opening the discharge passage and permitting the pressurized liquid to escape through the nozzle while being atomized.
In other proposed designs for dispensing pumps, a secondary piston is continuously engaged with a supply conduit, and a gravity-biased check valve is interposed between the pump chamber and the supply conduit to accommodate a refilling of the pump chamber. In most such designs, the check valve tends to undesirably move away from the seat when the pump is inverted if the pump chamber is not under sufficient pressure. If this occurs during the operation of the pump, the pump may malfunction or may not function as well as when the pump is in a generally upright orientation.
After the above-described pumps are operated to discharge the liquid by initially pushing the nozzle and connected piston downwardly, the finger force is typically removed or greatly reduced so as to permit the spring to urge the poppet back up against the piston and to continue urging the poppet, along with the engaged piston and nozzle, upwardly to the fully raised position (i.e., the initial, inactive "rest" position). As this occurs, liquid from the container is drawn up into the pump chamber.
The rate of refilling of the pump chamber with liquid from the container, and the amount of liquid that can be held in the pump chamber, depend upon the nature of the pump chamber and the pump features provided for accommodating the refilling flow of liquid. In some applications, it would be desirable to provide a relatively large amount of pump chamber capacity, and it would be desirable to refill the pump chamber as quickly and as fully as possible.
Another problem that must be overcome is the priming of the pump, especially where the pump chamber has a relatively large volume. Air and/or liquid vapor that is initially present in the pump chamber is compressed on the downward stroke of the piston. Owing to the high compressibility of the air, the resulting pressure is usually not great enough to move the poppet away from the piston to permit the discharge of the air out through the nozzle with a concomitant reduction in chamber pressure. Consequently, little or no liquid is drawn into the pump chamber during the return stroke of the piston, and the entrapped air merely expands to occupy the increasing volume of the pump chamber.
Various mechanisms have been proposed for venting air from the pump chamber to facilitate priming of the pump chamber with the liquid from the container. For example, the U.S. Pat. No. 3,774,849 issued to Michel Boris discloses the use of long vent ridges on the inner wall of a lower portion of the pump chamber This permits the compressed air to vent upwardly around the piston at the bottom of the piston stroke and to then flow into the container through an aperture in the upper part of the pump chamber. While this generally works well with the particular pump structure for which it was designed, it would be desirable to provide an improved structure for facilitating the air venting and liquid priming of a pump chamber, particularly a pump chamber having an increased capacity and increased liquid refill or priming flow rates.
It would also be beneficial if a pump having the above-described improved features could be provided with a configuration which, when the pump is in the unactuated position, has a reduced number of components that are in sealing engagement. Continuous engagement of seal parts over a long period of time can cause soft seal part material to creep and permanently deform. This can lead to reduced effectiveness of the sealing function between the engaged components.
In many applications, it is desired to produce a very highly atomized, fine mist. A problem with some pump designs is that the desired fine mist will be dispensed only if the operator pushes down the nozzle actuator with sufficient force and speed. Otherwise, liquid droplets may dribble out of the nozzle rather than the liquid being atomized in a fine mist--especially at the beginning and end of the liquid discharge. Thus, it would be desirable to provide an improved, finger-actuated pump for dispensing the liquid in a fine mist regardless of how slowly or discontinuously the nozzle actuator is pushed down by the user.
It would also be advantageous if an improved, finger-operated pump could be provided with a minimum number of small components that could be relatively quickly and easily assembled so as to facilitate fabrication of the pump.
Finally, it would be desirable to provide such an improved pump in which the configurations of the components could be simplified so as to facilitate fabrication of the components, as well as assembly of the components.